Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

Minor Loss in Pipe or Duct Components

Minor loss, pressure or head loss in pipe, tube and duct system components

Sponsored Links

Pressure loss in straight pipes or ducts are called major loss (linear loss). Pressure loss in components like valves, bends, tees and similar are called minor loss (local loss)

Minor loss can be significant compared to major loss. In fact - when a valve is closed or nearly closed - the minor loss is infinite. For an open valve the minor loss can often be neglected (typical for a full bore ball valve).

Minor Loss

Pressure drop or the minor loss in components correlates with the dynamic pressure in the flow and can be expressed as

pminor_loss = ξ (1/2) ρ v2                                       (1)


hminor_loss = ξ v2/ (2 g)                                         (2)


ξ = minor loss coefficient

pminor_loss = minor pressure loss (Pa (N/m2), psf (lb/ft2))

ρ = density (kg/m3, slugs/ft3)

v = flow velocity (m/s, ft/s)

hminor_loss = minor head loss (m, ft)

g = acceleration of gravity (9.81 m/s2, 32.174 ft/s2 )

  • 1 psf = 0.00694 psi (lb/in2)

The minor loss coefficient - ξ - values ranges from 0 and upwards. For ξ = 0 the minor loss is zero and for ξ = 1 the minor loss is equal to the dynamic pressure or head. The minor loss coefficient can also be greater than 1 for some components. 

Minor Loss Coefficient

The minor loss coefficient can be expressed as:

ξ = pminor_loss / ((1/2) ρ v2)                                             (3)


ξ = hminor_loss / (v2/ (2 g))                                              (4)

The minor loss in components depends primarily on the geometrical construction of the component and the impact the construction has on the fluid flow due to change in velocity and cross flow fluid accelerations.

The fluid properties - in general expressed with the Reynolds number - also impacts the minor loss.

The head loss information about components is given in dimensionless form and the information is based on experiments.

Equivalent Length

The minor loss in a system component can be converted to a length equivalent to a pipe or tube that would give the same major head loss.

Major head loss can be expressed as:

hmajor_loss = λ (l / dh) (v2/ (2 g))                                         (5)


hmajor_loss = major head loss (m, ft)

λ = friction coefficient

l = length of pipe or duct (m, ft)

dh = hydraulic diameter related to the pipe or tube with the component (m, ft)

If we want the minor loss to be equal to the major loss for a given equivalent length of pipe or duct - then

hminor_loss = hmajor_loss_eq                                            (6)


ξ v2/ (2 g)  = λ (leq / dh) (v2/ (2 g))                                 (6b)


hmajor_loss_eq = equivalent major head loss (m, ft)

leq = equivalent length of pipe or duct (m, ft)

Equivalent length can then be expressed by transforming (6b) to:

leq = ξ dh / λ                                                  (7)

The Total Head Loss of the pipe, tube or duct system, is the same as that produced in a straight pipe or duct whose length is equal to the pipes of the original systems - plus the sum of the equivalent lengths of all the components in the system.

Sponsored Links

Related Topics

Related Documents

Tag Search

  • en: minor loss pipe tube duct system
  • es: sistema de conductos de tubo tubo de pĂ©rdida menor
  • de: geringen Verlust Rohr Rohrleitungssystem
Sponsored Links

Search the Engineering ToolBox

Engineering ToolBox - SketchUp Extension - Online 3D modeling!

3D Engineering ToolBox Extension to SketchUp - add parametric components to your SketchUp model

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro .Add the Engineering ToolBox extension to your SketchUp from the SketchUp Pro Sketchup Extension Warehouse!

Translate this page to
About the Engineering ToolBox!


We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.

Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.

Google use cookies for serving our ads and handling visitor statistics. Please read Google Privacy & Terms for more information about how you can control adserving and the information collected.

AddThis use cookies for handling links to social media. Please read AddThis Privacy for more information.


This page can be cited as

  • Engineering ToolBox, (2004). Minor Loss in Pipe or Duct Components. [online] Available at: [Accessed Day Mo. Year].

Modify access date.

. .


3D Engineering ToolBox - draw and model technical applications! 2D Engineering ToolBox - create and share online diagram drawing templates! Engineering ToolBox Apps - mobile online and offline engineering applications!

Scientific Online Calculator

Scientific Calculator

11 19

Sponsored Links